23 research outputs found

    Chemical Evolution of Strongly Magnetized Quark Core in a Newborn Neutron Star

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    The chemical evolution of nascent quark matter core in a newborn compact neutron star is studied in presence of a strong magnetic field. The effective rate of strange quark production in degenerate quark matter core in presence of strong magnetic fields is obtained. The investigations show that in presence of strong magnetic fields a quark matter core becomes energetically unstable and hence a deconfinement transition to quark matter at the centre of a compact neutron star under such circumstances is not possible. The critical strength of magnetic field at the central core to make the system energetically unstable with respect to dense nuclear matter is found to be ∼4.4×1013\sim 4.4\times 10^{13}G. This is the typical strength at which the Landau levels for electrons are populated. The other possible phase transitions at such high density and ultra strong magnetic field environment are discussed.Comment: 18 pages, latex, eight EPS figures not included, available under request, REVTEX forma

    Kinetička svojstva F-centara pod utjecajem topline

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    The migration of colour clouds after the electron injection in pure and doped KCl and KBr alkali halides under thermal and field stresses is studied with an anode contact of spherical geometry. The diffusion coefficient of the colour clouds has been obtained using a derived analytical expression and the experimental data, and the activation energy of the colour centre was estimated. The dissociation energy values under thermal and field stresses for doped crystals are deduced through the mobility transport equation. The results indicate the effect of doping in an otherwise pure counterpart of the same crystals.Proučavamo premještanje oblaka boje nakon ubacivanja elektrona u čiste i punjene kristale alkalnih halida KCl i KBr, pod djelovanjem topline i električnog polja, uz primjenu kuglaste elektrode. Pomoću izvedene analitičke relacije i mjernih podataka odredili smo koeficijent difuzije oblaka boje i ocijenili aktivacijsku energiju centara boje. Primjenom jednadžbe pokretljivosti izveli smo vrijednosti disocijacijske energije pod toplinskim i električnim naprezanjem za punjene kristale. Podaci pokazuju učinak punjenja u odnosu na čiste kristale

    Kinetička svojstva F-centara pod utjecajem topline

    Get PDF
    The migration of colour clouds after the electron injection in pure and doped KCl and KBr alkali halides under thermal and field stresses is studied with an anode contact of spherical geometry. The diffusion coefficient of the colour clouds has been obtained using a derived analytical expression and the experimental data, and the activation energy of the colour centre was estimated. The dissociation energy values under thermal and field stresses for doped crystals are deduced through the mobility transport equation. The results indicate the effect of doping in an otherwise pure counterpart of the same crystals.Proučavamo premještanje oblaka boje nakon ubacivanja elektrona u čiste i punjene kristale alkalnih halida KCl i KBr, pod djelovanjem topline i električnog polja, uz primjenu kuglaste elektrode. Pomoću izvedene analitičke relacije i mjernih podataka odredili smo koeficijent difuzije oblaka boje i ocijenili aktivacijsku energiju centara boje. Primjenom jednadžbe pokretljivosti izveli smo vrijednosti disocijacijske energije pod toplinskim i električnim naprezanjem za punjene kristale. Podaci pokazuju učinak punjenja u odnosu na čiste kristale

    Prevalence of extended-spectrum beta-lactamases producing isolates obtained from patients of pediatric critical care unit in a tertiary care hospital

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    Background: Over the past decades, antibiotic-resistant Gram-negative bacteria commonly Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae have increased significantly. These microorganisms have great clinical importance because they increase hospital stay of the patients in the intensive care unit (ICU) leading to high morbidity and mortality. Because of their role in increasing morbidity and mortality, this study was performed to isolate extended-spectrum beta-lactamase (ESBL) producing Gram-negative bacilli screened by phenotypical method and further projected into molecular characterization by polymerase chain reaction. Aims and Objectives: The aims and objectives are to isolate the Gram-negative multidrug-resistant strains from clinically suspected bacterial infections in patients of neonatal, sick newborn, and pediatric ICU and to study antibiotic sensitivity pattern of isolated Gram-negative multidrug-resistant strains with special reference to molecular characterization. Materials and Methods: A total of 100 Gram-negative bacilli were isolated. Screening of ESBL positivity was done by double-disk synergy test (combined disc test method). Their antibiogram profile was interpreted. With the use of designed primers, 26 ESBL isolates each of E. coli and Klebsiella spp. were processed for molecular analysis of beta-lactamase family genes TEM and CTX-M. Results: Within the 100 samples, majority of the isolates (45%) were Klebsiella spp. and 40% was E. coli isolates. Highest ESBL-producing organisms were observed within E. coli (65%). Prevalence bla-TEM gene was highest followed by bla-CTX-M. These ESBL-producing organisms were found to be resistant to multiple classes of antibiotics. With extensive ESBL surveillance and proper usage of antibiotics, this threatening rise of antibiotic resistance can be mitigated. Conclusion: Gram-negative isolates showed high resistance to commonly used antibiotics. Significant proportions of them were MDR strains. Such high antibiotic resistance is associated with significant morbidity and mortality among pediatric population. MDR along with possession of ESBL associated resistance genes among Gram-negative bacilli pose a serious problem in therapeutic management of patients. Our study signifies that there is a high probability of Gram- negative bacilli to be multi-drug resistant and ESBL positive and earliest detection of such cases should be made

    Study of Phase Stability in NiPt Systems

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    We have studied the problem of phase stability in NiPt alloy system. We have used the augmented space recursion based on the TB-LMTO as the method for studying the electronic structure of the alloys. In particular, we have used the relativistic generalization of our earlier technique. We note that, in order to predict the proper ground state structures and energetics, in addition to relativistic effects, we have to take into account charge transfer effects with precision.Comment: 22 pages, 7 figures. Accepted for publication in JPC

    Phase stability analysis in Fe-Pt and Co-Pt alloy systems: An augmented space study

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    We have studied the problem of phase stability in Fe-Pt and Co-Pt alloy systems. We have used the orbital peeling technique in the conjunction of augmented space recursion based on the tight binding linear orbital method as the method for the calculation of pair interaction energies. In particular, we have generalized our earlier technique to take into account of magnetic effects for the cases where the magnetic transition is higher than the order disorder chemical transition temperature as in the case of Co3_3Pt. Our theoretical results obtained within this framework successfully reproduce the experimentally observed trends.Comment: 17 pages, 9 Figures. Accepted for publication in Journal of Physics : Condensed Matte

    Out-of-plane interface dipoles and anti-hysteresis in graphene-strontium titanate hybrid transistor

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    The out-of-plane electric polarization at the surface of SrTiO3 (STO), an archetypal perovskite oxide, may stabilize new electronic states and/or host novel device functionality. This is particularly significant in proximity to atomically thin membranes, such as graphene, although a quantitative understanding of the polarization across graphene-STO interface remains experimentally elusive. Here, we report direct observation and measurement of a large intrinsic out-of-plane polarization at the interface of singlelayer graphene and TiO2-terminated STO (100) crystal. Using a unique temperature dependence of anti-hysteretic gate-transfer characteristics in dual-gated graphene-on-STO field-effect transistors, we estimate the polarization to be as large as approximate to 12 mu Ccm(-2), which is also supported by the density functional theory calculations and low-frequency noise measurements. The anti-hysteretic transfer characteristics is quantitatively shown to arise from an interplay of band bending at the STO surface and electrostatic potential due to interface polarization, which may be a generic feature in hybrid electronic devices from two-dimensional materials and perovskite oxides

    Optical properties of perovskite alkaline earth titanates : a formulation

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    In this communication we suggest a formulation of the optical conductivity as a convolution of an energy resolved joint density of states and an energy-frequency labelled transition rate. Our final aim is to develop a scheme based on the augmented space recursion for random systems. In order to gain confidence in our formulation, we apply the formulation to three alkaline earth titanates CaTiO_3, SrTiO_3 and BaTiO_3 and compare our results with available data on optical properties of these systems.Comment: 19 pages, 9 figures, Submitted to Journal of Physics: Condensed Matte
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